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We utilize three parallel reservoir computers using semiconductor lasers with optical feedback and light injection to model radar probe signals with delays. Three radar probe signals are generated by driving lasers constructed by a three-element laser array with self-feedback. The response lasers are implemented also by a three-element lase array with both delay-time feedback and optical injection, which are utilized as nonlinear nodes to realize the reservoirs. We show that each delayed radar probe signal can be predicted well and to synchronize with its corresponding trained reservoir, even when parameter mismatches exist between the response laser array and the driving laser array. Based on this, the three synchronous probe signals are utilized for ranging to three targets, respectively, using Hilbert transform. It is demonstrated that the relative errors for ranging can be very small and less than 0.6%. Our findings show that optical reservoir computing provides an effective way for applications of target ranging.

We numerically investigate the complete chaotic synchronization mechanism of polarization mode of VCSEL with anisotropic optical feedback. Firstly, the synchronization quality of the x -linear polarization (LP) mode and the y -LP mode are both periodically changed with the angle θ between the polarizer and the light axes. Secondly, in a enough large scale region of the feedback coefficient and the injection current, where each LP mode can obtained good synchronization quality when the angle θ exists in the former half period region and the injection current is fixed at a certain value, which is over the threshold current. Under this condition, their synchronization quality is independent of the polarization states. By contrast, in the latter half period region of the angle θ where each LP mode can be obtained very instable and inferior synchronized quality. At last, the robustness of the synchronization scheme is sensitive to the internal and external parameter mismatch between the transmitter–VCSEL and the receiver–VCSEL.

Based on the SFM model [M. San Miguel, Q. Feng, J.V. Moloney, Phys. Rev. A. 52 (1995) 1728.], complete chaotic synchronization characteristics of linear-polarization (LP) Mode of the vertical-cavity surface-emitting semiconductor lasers (VCSELs) with isotropic optical feedback are numerically investigated. When the propagation time τ c of light from the transmitter to the receiver equals to the external cavity round-trip time τ , and the central frequency of the T_VCSEL matches that of the R_VCSEL, in large scale region of the feedback coefficient and the injection current where the x -polarization mode as well as the y -polarization mode obtains high synchronization quality at the same time. However, in the central frequency mismatch regions where the x - and y -polarization mode can obtain inferior synchronization quality at same time. But for τ c ≠ τ , each LP mode of the mixed polarization modes achieved inferior synchronization quality at the same time. Besides, with big enough injection current, the output of the system with the same central frequency in two lasers is entirely governed by the y -polarization mode when the feedback coefficient and Δ τ (= τ c − τ ) fixed at a certain value. So the system can realize steadily good synchronization of the completely dominant y -polarization mode. But the synchronization quality of the completely dominated y -polarization mode can be deteriorated by increasing absolute frequency detuning value. Besides, in positive frequency mismatch regions where the influence of the same frequency detuning value on the synchronization quality of the entirely governed y -polarization mode becomes smaller than in negative frequency detuning regions. At last, when τ is given and the central frequency of the T_VCSEL matches that of the R_VCSEL, the influence of the τ c is not a simple time-shift in the time-evolution of the receiver VCSEL, which has serious influence on the complete synchronization quality of each LP mode.

The dynamic single-mode and modulation performance of λ/4 phase-shifted distributed feedback laser diode with chirped grating (QWS-CG-DFB) are analyzed theoretically. The numerical simulation shows that, in contrast to purely QWS-DFB laser, the enhanced dynamic single-mode suppression ratio (SMSR) can be reached by QWS-CG-DFB laser. Under the smaller biasing current, the modulation band-width in presence of chirped grating is narrower, this difference shrinks for larger biasing current. For large signal modulation, the chirped grating is helpful to increase the output extinction ratio, but worsens the frequency chirping. The good dynamic characteristic can be obtained by selecting system parameters reasonably.

By using the coupled mode equations, the dynamic characteristics of λ /4 phase-shifted distributed feedback laser diode with distributed coupling coefficient (QWS-DCC-DFB) is analyzed. The numerical simulation indicates that, compared with purely QWS-DFB laser, the better dynamic single-mode can be achieved by QWS-DCC-DFB laser; Under the smaller biasing current, the modulation band-width is narrower, this difference shrinks for larger biasing current; For large-signal modulation, the distributed coupling coefficient is helpful to increase the output extinction ratio, but worsens the wavelength chirping. The good dynamic characteristic can be obtained by selecting system parameters reasonably. QWS-DCC-DFB laser would have potentials in optics communications because of better dynamic SMSR.

Based on the self-reproduction theory, a rational harmonic mode-locked semiconductor optical amplifier fiber ring laser was numerically investigated. The system parameters effects on pulse-amplitude equalization of rational harmonic mode locking was analyzed and the numerical result shows that the 2∼5 order rational harmonic mode-locked pulse with the small amplitude ripple can be obtained only by adjusting the system parameters.

It is found that the polarization of the VCSEL emitting chaotic carrier can be switched into the other arbitrary polarization by a reasonable selection of the applied electric field and the feedback coefficient.

Chaotic synchronization characteristics of the vertical-cavity surface-emitting lasers subjected by anisotropic optical injection are numerically investigated. First of all, the synchronization quality of the x-linear polarization (LP) mode and the y-LP mode are both periodically changed with the angle θ between the polarizer and the light axes. Second, in a enough large scale region of the feedback coefficient and the injection current, each LP mode can be obtained good synchronization quality when the angle θ exists in the former half periods region., in the case that their synchronization quality are independent of the polarization states of the lasers output. However, each LP mode can be achieved very instable and inferior synchronized quality, which is caused by the angle θ in latter half periods range.

The dynamic single-mode and modulation performance of λ/4 phase-shifted distributed feedback laser diode with chirped grating (QWS-CG-DFB) are analyzed theoretically. The numerical simulation shows that, In contrast to purely QWS-DFB laser, the enhanced dynamic single-mode suppression ratio (SMSR) can be reached by QWS-CG-DFB laser; Under the smaller biasing current, the modulation band-width in presence of chirped grating is narrower, this difference shrinks for larger biasing current; For large signal modulation, the chirped grating is helpful to increase the output extinction ratio, but worsens the frequency chirping.

The carrier lifetime is usually treated as a constant (called as the constant carrier lifetime assumption (CCLA)) during modeling theoretically the chaotic behaviors of semiconductor lasers. In this paper, after considering the actually recombination mechanism of the carriers in the semiconductor and the variation of the carrier lifetime with the time, the chaotic characteristics of semiconductor laser with optical feedback have been investigated numerically, and the obvious differences can be observed compared with those obtained with the CCLA.

We theoretically investigate the electro-optic coupling in an optical superlattice of linear chirped-periodically poled lithium niobate. It is found that the electro-optic coupling in such optical superlattice can work in a wide wavelength range. Some of examples, with bandwidths of 20, 40, 80, 120 nm, are demonstrated. The way to determine the electric field for perfect conversion between o- and e-ray and the method using apodized crystals of tanh profile to reduce the ripples are shown. As one of its applications, one kind of broadband Solc-type bandpass filter in optical communication range is proposed.